Note 3 - Revenue

9 Months Ended

Sep. 30, 2023

Notes to Financial Statements

Revenue from Contract with Customer [Text Block]

3.     Revenue

Disaggregated Revenue by Product Technology

The following table presents our revenues disaggregated by product technology:

	Three Months Ended				Nine Months Ended
	September 30,				September 30,
	2023		2022		2023		2022
Air Pollution Control
Technology solutions	$	1,910	$	1,904	$	7,449	$	5,711
Spare parts		1,339		384		1,938		742
Ancillary revenue		462		440		1,305		1,217
Total Air Pollution Control technology revenues		3,711		2,728		10,692		7,670
FUEL CHEM
FUEL CHEM technology solutions		4,277		5,289		10,044		12,250
Total Revenues	$	7,988	$	8,017	$	20,736	$	19,920

Disaggregated Revenue by Geography

The following table presents our revenues disaggregated by geography, based on the location of the end-user:

	Three Months Ended				Nine Months Ended
	September 30,				September 30,
	2023		2022		2023		2022
United States	$	5,640	$	6,972	$	15,937	$	14,939
Foreign Revenues
Latin America		157		56		310		185
Europe		1,001		613		2,400		1,939
Asia		1,190		376		2,089		2,857
Total Foreign Revenues		2,348		1,045		4,799		4,981
Total Revenues	$	7,988	$	8,017	$	20,736	$	19,920

Timing of Revenue Recognition

The following table presents the timing of our revenue recognition:

	Three Months Ended				Nine Months Ended
	September 30,				September 30,
	2023		2022		2023		2022
Products transferred at a point in time	$	6,078	$	5,969	$	13,287	$	14,065
Products and services transferred over time		1,910		2,048		7,449		5,855
Total Revenues	$	7,988	$	8,017	$	20,736	$	19,920

Contract Balances

The timing of revenue recognition, billings, and cash collections results in billed accounts receivable, unbilled receivables (contract assets), and customer advances and deposits (contract liabilities) on the Condensed Consolidated Balance Sheets. In our Air Pollution Control (APC) technology segment, amounts are billed as work progresses in accordance with agreed-upon contractual terms. Generally, billing occurs subsequent to revenue recognition, resulting in contract assets. For the FUEL CHEM technology segment, deliveries made in the current period but billed in subsequent periods are also considered unbilled receivables (contract assets). These assets are reported on the Condensed Consolidated Balance Sheets on a contract-by-contract basis at the end of each reporting period. At September 30, 2023,  December 31, 2022, and December 31, 2021, contract assets for APC technology projects were approximately $1,944, $3,082, and $1,277, respectively. There were no contract assets for the FUEL CHEM technology segment as of  September 30, 2023,  December 31, 2022, and December 31, 2021.  

However, the Company will periodically bill in advance of costs incurred before revenue is recognized, resulting in contract liabilities. These liabilities are reported on the Condensed Consolidated Balance Sheets on a contract-by-contract basis at the end of each reporting period. Contract liabilities were $1,365, $372, and $390 at September 30, 2023,  December 31, 2022, and December 31, 2021, respectively, and are included in other accrued liabilities on the Condensed Consolidated Balance Sheets.

Changes in the contract asset and liability balances during the nine-month period ended September 30, 2023, were not materially impacted by any other items other than amounts billed and revenue recognized as described previously. Revenue recognized that was included in the contract liability balance at the beginning of the period was $0 and $368 for the three and nine months ended September 30, 2023, respectively, and $131 and $381 for three and nine months ended September 30, 2022, respectively, which represented primarily revenue from progress towards completion of our APC technology contracts.

As of September 30, 2023 and December 31, 2022, we had no construction contracts in progress that were identified as a loss contract. 

Remaining Performance Obligations

Remaining performance obligations represents the transaction price of APC technology booked orders for which work has not been performed. As of September 30, 2023, the aggregate amount of the transaction price allocated to remaining performance obligations was $5,624. The Company expects to recognize revenue on approximately $4,874 of the remaining performance obligations over the next 12 months with the remaining recognized thereafter. 

Accounts Receivable

The components of accounts receivable are as follows:

	As of
	September 30, 2023			December 31, 2022
Trade receivables	$	5,717		$	4,605
Unbilled receivables		1,944			3,082
Other short-term receivables		145			152
Allowance for credit losses		(110	)		(110	)
Total accounts receivable	$	7,696		$	7,729